In some implementations, the rear exterior surface of the device housing 702 includes a plurality of recesses 724. For example, the plurality of wire terminals 720 is disposed within a first recess 724A, and separated by a separation 730 that protects the lines connected to the first and second terminals of the plurality of wire terminals 720 from being shorted to each other. A height of the separation 730 may be smaller than a depth of the first recess, and the depth of the first recess 724A is configured to be greater than a height of a connection formed between the plurality of wire terminals 720 and the power supply or ground line. Specifically, in the above example, when the screw fastener is used to fix the fork terminal of the power supply or ground line onto one of the plurality of wire terminals 720, the depth of the first recess 724A is configured to be greater than a total height summing a thickness of the fork terminal and a height of a screw head of the screw fastener. As such, when the power supply and ground lines are connected i. e.